Stormy week ahead for the Med

Su Campu

There's a stormy week ahead for the southern Med as the jetstream remains well to the south and is intensifying to 200knots, ensuring plenty of cyclogenesis for Iberia, Italy, Greece and North Africa. There'll be some really nasty weather in Greece Monday, as the depression currently over eastern Morocco deepens and moves northeastwards, bringing heavy rain and severe winds. At the same time another depression affecting the Balearics moves eastwards towards Sardinia and Italy.

I would expect to see some reports of deaths in the news this week.

Su Campu

ESTOFEX are forecasting Level 2 severe weather for Tunisia and the central Med (including Malta) over the next 24hrs, with large hail, severe wind gusts, tornadoes and excessive rainfall expected.

http://www.estofex.org/

Storm Forecast
Valid: Sun 07 Mar 2010 06:00 to Mon 08 Mar 2010 06:00 UTC
Issued: Sat 06 Mar 2010 22:38
Forecaster: SCHLENCZEK

A level 2 is issued for most parts of E Algeria and Tunisia for large hail, severe wind gusts, tornadoes and excessive rainfall.

A level 1 is issued for Sicily mainly for excessive rainfall and severe wind gusts.

A level 1 is issued for the C Mediterranean and S Greece mainly for severe wind gusts and tornadoes.

SYNOPSIS

A large upper trough, filled with cold air, is present over east-central Europe. At its southern flank, a strong westerly upper jet stretches from SW France to the Black Sea. CAA will be strongest over SE Europe in the wake of a low pressure system over the eastern Ukraine which will move to the northeast. Warm air with 850 hPa temperatures around 10°C is located over Tunisia / Libya and will be advected towards S Greece and Crete during the forecast period.

DISCUSSION

...S Iberia...

Near the southern tip of an upper trough over SW Iberia, steepening lapse rates will lead to a few hundred J/kg CAPE. 0-6 km deep layer shear should stay below 15 m/s and some briefly organised multicells may develop. Severe weather is not likely but a few waterspouts are not ruled out.

...NE Algeria, Tunisia, C Mediterranean...

Ahead of a low pressure system which is centered over S Algeria, hot and moist air is advected into parts of NE Algeria and N Tunisia. GFS predicts moderate instability with MLCAPE in order of 500 J/kg in the vicinity of an upper vort-max associated with an upper shortwave trough. Low level winds will back to the east / northeast ahead of the cold front and even though the Mediterranean Sea is rather cool, this will lead to a mixing ratio in order of 10 g/kg. As convection developed also on Saturday evening in the warm sector of the low, forcing is probably sufficient for convective initiation. From 850 to 600 hPa, the Saturday 12 UTC DAAG sounding shows an elevated mixed layer in the warm sector of the low which will overspread the discussed area in the morning / afternoon hours. A westerly 25 m/s upper jet near 500 hPa leads to very strong deep layer shear (20 - 30 m/s) and very high values of 0-3 km SRH (close to 600 m2/s2 over E Tunisia). Any storm in this environment may become supercellular, posing a threat of (very) large hail, damaging wind gusts and tornadoes. During the afternoon, storms close to the centre of the low pressure system will likely merge into a MCS with severe wind gusts and heavy convective rainfall being the main threat. Later in the period, storms will tend to weaken as instability and forcing decrease towards the central Mediterranean and W Ionian Sea but an isolated excessive rainfall / severe wind gust event over Sicily is not ruled out.

...Ionian Sea, SW / S Greece...

In the late evening / night hours, remnants of the convective systems over Tunisia / C Mediterranean will cross the Aegean Sea and parts of Greece. Even though instability and forcing are slightly reduced, very strong winds at mid levels (around 30 m/s at 700 hPa) will lead to an enhanced risk of severe wind gusts. 0-1 km SRH forecast by GFS should be in order of 600 - 800 m2/s2 which is favourable for strong low level rotation. If convective cells stay quite discrete, they will likely become tornadic supercells with strong tornadoes (F2 - F3) possible. At this moment, confidence is too low that discrete storms indeed develop in this region and only a level 1 is issued. An upgrade may follow in the afternoon / evening.

Su Campu

The storminess continues, with 3 different depressions now in the Med. Heavy rain the main problem throughout, with the possibility of coastal tornadoes in Ionian coastal areas.

Storm Forecast
Valid: Mon 08 Mar 2010 06:00 to Tue 09 Mar 2010 06:00 UTC
Issued: Sun 07 Mar 2010 19:57
Forecaster: DAHL


A level one was issued across the Ionian and Aegean regions for marginally severe wind gusts and excessive convective rainfall.

A level one was issued across the western Mediterranean Sea for marginally severe wind gusts and excessive convective rainfall.

A level one was issued across the southern Iberian peninsula for excessive convective rainfall.

SYNOPSIS

Most of the European continent is dominated by a sturdy high-pressure area, filled with continental polar air masses, reaching well into the Mediterranean regions. A marked air-mass boundary exists between these polar air masses and moist subtropical air over the Mediterranean. This boundary should stretch from southern Iberia eastward across the Aegean regions into the Black-Sea area on Monday afternoon. The main upper frontal zone is aligned with the low-level thermal boundary. Several imbedded vorticity maxima will support SFC cyclogenesis along the SFC front, resulting in a southward shift of this front over the western Mediterranean regions late in the period.

The subtropical air south of the boundary is essentially moist-neutrally stratified, with weak CAPE indicated by the models ahead of the upper vorticity maxima.

DISCUSSION

... Ionian and Aegean regions ...

Ahead of the low-pressure system that will reach the Aegean region late in the period, steep mid-level lapse rates from the Sahara desert will be integrated into the circulation (per GFS). Comparatively weak low-level moisture should limit the overall destabilization, however, so that CAPE will be unlikely to exceed a few 100 J/kg.

GFS simulates a rather patchy CAPE field, as well as several rather small-scale bulk-shear maxima, with transient/partial overlaps of maxima of both fields. This suggests that the average DLS may be somewhat limited, but temporarily become favorable for storm organization.

Although the majority of the cells will likely be rather weak, some of them may organize into line segments and mesocyclonic storms. The main threat should be marginally severe outflow winds, though small hail and maybe a brief tornado or two cannot be excluded, especially in coastal regions. Heavy and prolonged, convectively-augmented rain may occur especially in upslope-flow regimes over the southern Balkan States.

... western Mediterranean regions ...

A somewhat weaker cyclone will exist farther upstream over the western Mediterranean. Given the lack of steep lapse rates, the convective threat should be considerably smaller than with the system farther east. However, 25 m/s DLS suggest that rather well-organized (albeit comparatively small) multicells and also mesocyclonic storms may develop, posing a threat primarily of severe wind gusts. Especially in the WAA regime of the cyclone, convectively-augmented precip may exceed severe probabilities.

... southern Iberian peninsula ...

Yet another SFC low, reaching the Iberian Peninsula late in the day, will affect the forecast region on Monday. This system accomodates quite moist subtropical/Atlantic air masses in its warm sector. Although instability will likely be minimal, it is anticipated that weak and probably elevated convection will be imbedded in warm- and cold-frontal rain bands. Strong mesoscale ascent should support large amounts of precip over the southern portions of Iberia, which will likely exceed LVL1 criteria. Shear profiles will be supportive of severe evolution, but it does not seem that deep SFC-based convection will form.

DeVore

Fairly mad down here at the moment alright. I'm in Malta, in a top floor apartment.

Tornados though?!? Holy ****..... I have to fly out tomorrow!

DeV.

Su Campu

Rainfall amounts for the 24hrs to 6am this morning are around 30-50mm for the southern Med, with strong winds gusts in parts of the Greek Islands.

Rhodes/Paradissi (11 m) 65 mph
Kithira (167 m) 60 mph
Iraklion (39 m) 53 mph
Chania Souda (151 m) 52 mph
Kos AP (129 m) 50 mph
Alexandroupoli (Airport) (3 m) 46 mph
Limnos AP (4 m) 43 mph
Elefsis AP (31 m) 42 mph
Preveza/Aktion (4 m) 40 mph